Groundwater, surface water, and wastewater may contain inorganic and organic toxic compounds, such as but not limited to arsenic, selenium, uranium, mercury, chromium, pesticides, and chlorinated and nitro organic chemicals, due to natural and anthropogenic sources. To protect human health and the environments, the contaminants have to be removed from drinking water and wastewater to meet government imposed regulatory limits.
Zero valent iron or metallic iron is an economic and effective material for treatment of inorganic and organic pollutants in water, soil, and gas. Iron products, in nano particulate, fine powder, granular, and scrape forms, have been used for treatment of arsenic, heavy metals, and organic contaminants. However, nano iron particles are expensive and can be readily oxidized. Fine iron powder is difficult to be used in filters and in situ permeable reactive barriers because of the low hydraulic conductivity of iron particles. Furthermore, these iron particles will fuse into a mass due to formation of iron oxides. Such masses have large iron particles and scraps have low specific surface and reactivity.
To solve the low hydraulic conductivity and fusion problems of small metallic iron particles, it is necessary to provide the embodiments of the present invention, as other attempts to solve such problems, as noted below have not achieved satisfactory results.
U.S. Pat. No. 6,387,276 pertains to a method for mixing zero valent iron filings with a sand component to achieve the desired permeability. The mixture is used in ex-situ water treatment systems and in situ permeable wall or reactive barrier groundwater treatment systems for removal of arsenic.
U.S. Pat. No. 6,942,807 pertains to a water filtration apparatus, comprising a vibration device attached to a filtration vessel and a bed of metallic iron particles within said vessel, for treatment of water contaminated with heavy metals and organic compounds. The vibration prevents the fusion of iron particles during filtration treatment of water.
U.S. Pat. No. 6,602,320 pertains to a method for producing reduced iron comprises agglomerating a raw material mixture containing a carbonaceous reducing agent and an iron oxide-containing material into small agglomerates, heating the agglomerate within a heat reduction furnace, thereby reducing the iron oxide in the agglomerate to produce solid reduced iron, or further heating the solid reduced iron, melting the metallic iron produced by the reduction, and coagulating the molten metallic iron while separating the slag component contained in the small agglomerates to provide granular metallic iron.
U.S. Pat. No. 7,611,637 pertains to methods for preparing generally spherical hollow and/or porous zero valent iron particles having a diameter no larger than about ten millimeters and a porosity greater than 0.1 for treatment of contaminated water. The zero valent iron particles are produced using a sacrificial substrate and thermal treatment, comprising the steps of: a) preparing a generally spherical substrate of a material that can be converted to volatile matter or a gas at elevated temperature; b) coating said substrate with metallic iron to form a substantially continuous layer at least 0.25 nm thick; c) exposing said coated substrate to one of a chemical reagent or a temperature high enough to remove said substrate to form a hollow iron particle; and d) reducing iron oxides in said particle to metallic iron.
U.S. Pat. No. 9,452,413 pertains to a porous and permeable composite for treatment of contaminated fluids. The composite includes a body of iron particles and 0.01-10% by weight of at least one functional ingredient distributed and locked in the pores and cavities of the iron body. The iron body is prepared using compaction and/or heat to form a porous and permeable iron particle structure.
Various devices are known in the art. However, their structure and means of operation are substantially different from the present disclosure. The other inventions fail to solve all the problems taught by the present disclosure. At least one embodiment of the present invention is presented below and will be described in more detail herein.